1. Field of the Invention
The present invention is related to the use of guides for placement of guide wires in orthopedic surgery, and more particularly to the use of a guide clamp for placement of a guide wire during femoral head resurfacing surgery.
2. Description of Related Art
When severe hip joint problems are encountered, it is sometimes necessary to replace a portion of the hip joint; either the ball or the socket or both. One generally used hip joint replacement technique involved removal of a head and neck of the femur, and the insertion of a long angled and tapered metal prosthesis into the central “intramedulary” canal at the open upper end of the main straight portion of the femur. This femoral prosthesis typically had a relatively small metal ball at its upper end which mated with a small plastic socket mounted on the hip side of the joint. However, this “total” hip replacement technique was drastic, involving complete removal of the head and neck of the femur, and made any subsequent hip joint problems difficult to handle.
U.S. Pat. No. 4,123,806 to Amstutz, et al., discloses an early femoral prosthesis having a cobalt-chromium-molybdenum metallic shell of generally hemispherical shape. This femoral prosthesis is designed on the principle of removing all non-viable femoral head bone, but also preserving as much of the head and neck as possible.
In a more recent development, U.S. Pat. No. 6,156,069 to Amstutz (“the '069 patent”), which is commonly assigned and hereby incorporated herein by reference, discloses a metal-to-metal surface hip joint replacement. As shown in FIGS. 1-3 of the '069 patent, the metal-to-metal replacement includes a metallic (e.g. cobalt-chrome alloy) femoral prosthesis 22 and an acetabular prosthesis 40 also constructed of a metal material. Notably, FIG. 1 of the '069 patent shows that placement of the femoral prosthesis requires shaping of the femoral head 30 to fit a stem 24 and internal geometry of the femoral prosthesis. Shaping of the femoral head requires the use of various cutting and drilling tools. Accurate completion of such shaping procedures is aided by the accurate placement of a Steinman pin or guide wire 74 which guides the cutting and drilling tools. The '069 patent discloses what has become commonly known as femoral head resurfacing.
A clamp 62 is used to facilitate centering and placement of the guide wire, as shown in FIG. 9 of the '069 patent. The clamp includes a pair of jaws 64 that are supported by support member 68 and at pivot points 66 that allow pivotal rotation of the jaws with respect to the support member. Such rotation allows the jaws to engage the neck 32 of the femur 28. The jaws are advanced and retracted by rotation of a handle 70 which advances a threaded actuator 76 through the body and moves a camming surface 72 attached thereto. The camming surface, in turn, drives opening and closure of the jaws about the neck. After the clamp is secured, the pin or guide wire is inserted into, and advanced through, collinear guide openings defined in the handle and threaded actuator until hitting an entry point 78 on the femoral head 30. Advantageously, the ability of the clamp to engage and hold the guide openings in a fixed position relative to the femur promotes the accurate insertion of the guide wire or pin.
Despite the advantages of the clamp disclosed by the '069 patent, further improvements in the adjustability of positioning of pins and guide wires to improve the accurate placement of femoral prostheses are always desirable. It would be advantageous, therefore, to have a clamp and method with improved options to easily and accurately place a guide wire or pin which is subsequently used to guide femoral head resurfacing.